Dimpling tool for aiding in the removal of fasteners



May 23, 1950 E. E. CAVALLIN 2,508,373

7 DIMPLING TOOL FOR AIDING IN THE REMOVAL OF FASTENERS Filed July 10.. 1946 mmvrox. EDWARD E. GAVALLl/V I ATTORNEY f atented may 23,

DIMBLING-KI100L rolmlnmemmns REMOVA OF AQ' IENEB' Edward ErCavallinj-Sanlliego} Calif. .-.Ap 1icamnsu1y 10. 46 -etie1Ndefilili? ve lei-antes:mere-tile act of March 3, 1883, as .iElilZiiBlldQEl-TA-QIH .30, 92 13"70"0-;".G-;.757)

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TIhis invention relates to-a tool; and morepar- "ticul'arly to a dimpling tool for' aiding in; thememeter of -fa'stenersof the -dzustype, as exemplified 11 1,986,329. f =the dzus type,' commonly used to al a tche'saonaircraftaare subject -;to*wear 'andmust often he replaced-mbe'fore=.=the "*ha'tcli tself' wea'rs out; In the pastyiti has'been "'"clist mary to":drivethefasten r out with alhammer blowi tlierebymutilating; to a ce'rt'airr 'extent,

- the edges} of the 'hole' inwhichthe-z-fastenernwas placed: *Ther-eaftr the-setting of a new replacement fastener was somewhat unsatisfactory because of thetorn and jagged hole edge.

It! iS-:=.2;l1'-;ObjCt of thisinvention tic-provide a tool whereby the hole in which a; dzus fastener is located may-besmoothly and uniformly enlarged without damage to the'm'etal surrounding the ,llq It is dimpling the edge of a hole while a dzus fastener is still located in the hole.

In accomplishing these and other objects of the present invention, I have provided improved details of structure, the preferred form of which is illustrated in the accompanying drawing, wherein:

Fig. 1 shows a perspective view of the dimpling :tool of this invention;

Fig. 2 shows the manner in which the .tool of Fig. l is applied under the head of a dzus fastener preparatory to dimpling the edge of the fastener .hole; and

Fig. 3 illustrates a cross-section of the tool and fastener to which it is applied, taken along line f33 of Fig. 2.

Dzus fasteners, such as are used to hold hatches to the sides of an aircraft, are of two types. One type employs a grommet which is inserted in the hole at the same time that the fastener is applied thereto. The removal of this type of fastener, for replacement with a new fastener, is accomplished by simply striking with a hammer to drive the fastener from the hole. This mutilates the grommet but leaves the edge of the hole sub- ;stantially intact. A new grommet and fastener may then be applied.

The second type of fastener does not employ a grommet, using merely the edge of the fastener hole as a holding means for the fastener. It is to this type that the tool of this invention is applicable.

In originally applying a dzus fastener to a hole in a hatch, the hole is first dimpled by applying a dimpling tool to the edge of the hole and unia'r'iotherobject to pr'ovide a toolcap'able of formly bendingback edge..-until-.the;ho1e.i8

x'rby.thezantiedimpling:

a;.l-arge1:enough .to: pass ..the'1.body. of ethe fastener. herfastener lisltheniinserted .andthe edge .of the hole returned to normal by use of an :anti- .dimpling; tool.

's- Whenitbecame necessarytoreplacea fastener,

naidimpling tool. couldinotbe :used. because; its pplication ztoithe .edge ofithehole was prevented a. by .theapresence of thesfasteneruitself. :.As, a;r.e-

suit, standard practice was toz-zsimplyedriyethe fastener out: of. the; hole iwithoutatfirst. dimpling "'theisedgeb'I his left theledge. jagged; ;.and :torn; so

hat ritwasinoaonly- -les spat-1e. to be reformed but even .afterireformae tion, it provided poore supportlfor. therfastener because of the uneven: ars therein.

In,accordance;= Wlitii hen-present invention, a

. .gdimpling tool. isiprovidedcomprising; a ring xhav- :ringza taperedzcrosssection.which:may.be inserted between the he'ad of a" dzus. fastener andthe metal plate containing the'fastenermounting hole. A blow on the head of the fastener causes the tool to dimple the edgeaofthe ,hole ,'thereby enlarging it to permit ifree;extraction of the fastener to be replaced. The ring isqs'plitinto two segments to permit it to be applied around the fastener.

Referring now to the drawing, the'tool is shown in Fig. 1 comprising a metal ring l0 consisting of two opposed semi -c'ircular segments f i l and II. In cross-section, each segment has a flat surface E3 on the upper side thereof and a rounded or convex surface 54 on the under side thereof, the latter surface tapering toward the outside of the ring, so as to be disposed generally at an acute angle with respect to the axis of the ring. It will be readily seen from Fig. 3 that the above construction gives the ring a thickness; in a direction parallel to the axis, which is greater at the inner edge than at the outer edge. 0n the outer edges- I5 and I6 of segments H and 12, respectively, are connected arms I! and 18. respectively, lying in a plane substantially parallel to that of ring it. Arms I! and iii are preferably formed from a single piece of resilient material, such as heavy wire, having a loop l9 therein disposed at the extreme end of the tool from ring l0. Loop l9 forms a spring means for biasing apart, to a limited extent, segments H and I2 of ring Ill.

Operation bringing segments H and I2 together under head 2| of fastener 20.

In this position, as shown in Fig. 3, the tapered surface M of ring In is brought to bear against the edge of hole 22 in which fastener 20 is mounted. A sharp blow with a hammer against head 2| drives the tapered surface of ring l0 against the edge of hole 22 in metal sheet 23, enlarging the hole to a diameter slightly exceeding that of body 24 of fastener 20. After fastener 20 has been removed, the edge of the dimpled hole presents a neat and unjagged appearance as shown at 25.

Following removal of fastener 20 by the use of this tool, the hole is ready to receive a new fastener. At this point the hole presents the same appearance as it did during the original installation of the fastener, when a standard dimpling tool was used.

Without this tool, it has been necessary in the past to strike a heavy blow against body 24 of fastener 20, driving the shoulder of body 24 against the edge of hole 22 and enlarging the hole in an uneven manner leaving a jagged edge shown at 26.

While I have shown but one embodiment of my an invention, it is susceptible to modification without departing from the spirit of the invention. I do not wish, therefore, to be limited by the disclosures set forth, but only by the scope of the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

I claim:

1. A dimpling tool for aiding in the removal of fasteners of the dzus type comprising a split ring, the thickness of said ring in a direction parallel to the ring axis being greater at the inner edge than at the outer edge, and means connecting the two parts of the split ring and permitting the ring to be opened for insertion under the head of a fastener of the dzus type.

2. A dimplin tool for aiding in the removal of fasteners of the dzus type, comprising a ring split into two segments, the thickness of said ring in a direction parallel to the ring axis being greater at the inner edge than at the outer edge; a pair of arms connected at their inner ends, respectively, to said segments, the other ends of said arms being connected together; and spring means at the common connection between said arms tending to bias said segments apart.

3. A dimpling tool for aiding in the removal of fasteners of the dzus type, comprising a ring split into two segments, the under surface of the ring being generally convex with respect to the axis of the ring; a pair of arms connected at their ends, respectively, to said two segments, the other ends of said arms being connected together; and spring means at the common connection between said arms tending to bias said segments apart.

4. A dimpling tool for aiding in the removal of fasteners of the dzus type, comprising a ring split into two segments, the under surface of the ring being generally convex with respect to the axis of the ring, and means connecting said segments and permitting the ring to be opened for insertion under the head of a fastener of the dzus type.

EDWARD E. CAVALIJN.

REFERENCES CITED UNIL ED STATES PATENTS Name Date Lindsley Aug. 18, 1885 Number 

